1. Field of the Invention
The present invention relates to a floating-type head slider which is, for example, provided in a magnetic recording/reproducing apparatus and configured to have a magnetic head float over a surface of a recording medium at the time of driving, and a recording/reproducing apparatus having such a head slider.
2. Description of the Related Art
Generally, in a recording/reproducing apparatus such as a hard disk device, it is necessary to avoid wear/damage due to contact of a surface of a magnetic disk with a magnetic head. Accordingly, a floating-type slider having an air bearing surface (air lubricating surface) is provided for a magnetic head so as to ensure a predetermined gap between the magnetic head and a magnetic disk by means of an air pressure at the time of disk rotation, which results in information recording in a non-contact manner.
FIG. 13 is a perspective view showing a general slider 100 viewed from underneath. As shown in FIG. 13, the slider 100 is arranged to have rails 101a, 101b each having an air bearing surface (air lubricating surface), and a magnetic head 102 is fixed at an end surface of the rail 101b. And, as shown in FIG. 14, an airflow generated when a magnetic disk 103 is rotated produces a floating power (pressure) onto the rails 101a and 101b. The floating power makes the slider 100 and the magnetic head 102 float above a surface of the magnetic disk 103 with a slight gap (flying height) therebetween. There have been realized a flying height of about 0.04 xcexcm in a currently commercially available hard disk drive, and that of about 0.02 xcexcm in a study level.
According to a hard disk device of a floating head type, as described above, even in a case of a disk having unevenness on a surface thereof, it is possible to reduce a spacing loss by making the magnetic head follow the unevenness on the surface. In addition, it is possible to prevent a magnetic head from contacting with a surface a magnetic disk so as to prevent the magnetic disk from wear and damage.
By the way, as described above, the flying height of the slider is significantly minute. Accordingly, even in a case where a quite small amount of dust comes into the hard disk device, there may be caused a serious damage to the hard disk device. Therefore, it is a usual manner that a hard disk device is assembled in a highly controlled clean room.
However, in a removable-type hard disk device in which a disk can be attached/detached, there is always a large slot provided to the hard disk device for inserting and pulling out a recording medium, and, inevitably, dusts of an amount existing in a usual life environment always come into the device. Once a dust comes into the air bearing surface of the floating-type head slider, the amount of the flying height changes and data cannot be recorded and read correctly, or further, the data may be damaged due to the contact of the slider with the disk. Accordingly, in a removable-type hard disk device employing a floating-type head system, dust control becomes the most important problem to be solved.
In addition, in late years, there are many cases using a personal computer in the open air along with the significant popularization of notebook type personal computers. In a case of taking out and using a personal computer in the open air, possibility of various kinds of vibration and shock to be given to a built-in hard disk device increases, which brings a problem of damages to the hard disk due to vibration caused by a slider. Because a spring hardness itself of an air film generated by air pressure caused between a slider and a magnetic disk at the time of disk rotation has a hardness of about 50 times of that of a suspension which supports a car, the slider hardly vibrates widely due to some vibration or shock externally given. However, in a case where a housing of the personal computer hits some corner or a case where the personal computer itself hits the ground, the slider may vibrate widely and contact with the hard disk. Accordingly, it is quite dangerous to mount a hard disk device in a personal computer for outdoor use, in view of data protection.
However, in consideration of an advantage of the hard disk device being high-speed processing, large capacity and low in price, even in a case of a notebook type personal computer premised to be used outdoors, there is no other choice than employment of a hard disk device. Accordingly, a hard disk device is required to secure reliability in a case of receiving external vibration and shock, in other words, it is quite important to prevent a slider from contacting with the hard disk.
The present invention is made in consideration of the above-described problem to be solved and there are provided a floating head slider having high reliability even in an environment to which dust may come into and a recording/reproducing apparatus in which such a floating head slider is employed.
In order to solve the above problem, according to a first essential view point, there is provided a floating-type head slider having at least a rail plane which functions as an air bearing in accordance with a kinetic pressure of an air flow caused by rotation of a recording medium, which supports a recording/reproducing device for recording and reproducing information keeping a predetermined gap between the device and a surface of the recording medium, wherein all of or almost all of edges (i.e., rails) of the rail plane comprises only a plurality of straight lines and arcs each being a part of one of an ellipse and a circle, for smoothly connecting ends of two of the straight lines. Herein, it is preferable that an edge of the rail plane which is positioned at a same height level is configured to be continuously endless.
According to such configuration, in a case of sudden contact of a slider with a magnetic disk due to vibration and shock given to the slider, it becomes less possible to damage a surface of a disk by configuring the edge (rail) of the rail plane with only a plurality of straight lines and arcs each being a part of an ellipse or a circle for smoothly connecting ends of two of the straight lines. Incidentally, it is preferable that the head slider comprises a plurality of rail planes with a plurality of height levels.
Furthermore, it is desirable that an area of a rail plane which comes closest to the magnetic disk is 30% or more, more preferably, 40% or more of the entire area, which functions as the air bearing, of the slider.
According to such a configuration, in a slider having multi-level edges (rails), when an area of a first rail plane which comes closest to the magnetic disk is set to be as large as possible against to an entire area of an air bearing surface of the slider, it is possible to reduce variation in floating height even in a case where a dust sticks onto the rail plane. In addition, even in a case where the slider comes into contact with the disk, because the contact pressure between the slider and the disk is kept low, it becomes less possible that the disk is damaged.
In addition, it is desirable that the rail plane comprises at least leg portions provided at a center portion and both end portions opposing to a moving direction and a connecting portion provided ahead in the moving direction for connecting among the leg portions. According to such construction, the rail plane has a comb-like shape.
In addition, according to a second essential view point of the present invention, there is provided a recording/reproducing device having a floating-type head slider having at least a rail plane which functions as an air bearing in accordance with a kinetic pressure of an air flow caused by rotation of a recording medium, which supports a recording/reproducing device for recording and reproducing information keeping a predetermined gap between the device and a surface of the recording medium, wherein an edge of the rail plane comprises only a plurality of straight lines and arcs being a part of an ellipse or a circle, for smoothly connecting ends of two of the straight lines.
According to such constitution, a recording/reproducing device having the floating-type head slider according to the first point of view can be provided.
As described above, according to the present invention, a floating-type head slider having high reliability even in an environment into which a dust may come and a recording/reproducing apparatus in which such a floating-type head slider is employed can be provided.
Incidentally, the other characteristic features of the present invention and significant effect introduced by the present invention can be understood by the following description of embodiments of the present invention and attached drawings.